1. Field of the Invention
The present invention relates generally to detection of electromagnetic radiation that may be harmful to a user or electrical device and, more specifically, to a device for detecting the magnitude, duration, repetition, and emission direction of the electromagnetic radiation and informing the user of same.
2. Description of Related Art
The electromagnetic pulse (EMP) effect was first observed during the early testing of high altitude airburst nuclear weapons. The effect is characterized by the production of a very short (e.g., hundreds of nanoseconds) but intense electromagnetic pulse, which propagates away from its source with ever diminishing intensity, governed by the theory of electromagnetism. The EMP is in effect an electromagnetic wave resulting in an electromagnetic field sufficiently strong to produce short-lived transient voltages, of thousands of volts, for example, on exposed electrical conductors, such as wires, or conductive tracks on printed circuit boards, where exposed.
The result may be irreversible damage to a wide range of electrical and electronic equipment, particularly computers and radio or radar receivers. Subject to the electromagnetic hardness of the electronic equipment, a measure of the equipment's resilience to this effect, and the intensity of the field produced by an EMP emission, the equipment can be irreversibly damaged or, in effect, electrically destroyed. The damage inflicted is not unlike that experienced through exposure to close proximity lightning strikes, and may require complete replacement of the equipment, or at least substantial portions thereof.
Commercial computer equipment is particularly vulnerable to EMP effects, as it is largely built up of high-density Metal Oxide Semiconductor (MOS) devices, which are very sensitive to exposure to high voltage transients. What is significant about MOS devices is that very little energy is required to permanently wound or destroy them, as any voltage typically in excess of tens of volts can produce an effect termed gate breakdown, which effectively destroys the device. Even if the pulse is not powerful enough to produce thermal damage, the power supply in the equipment will readily supply enough energy to complete the destructive process. Affected devices may still function, but their reliability will be seriously impaired. For example, the circuitry may be undamaged but data corruption has occurred. Shielding electronics by equipment chassis provides only limited protection, as any cables running in and out of the equipment will behave very much like antennae, in effect guiding the high-voltage transients into the equipment.
Computers used in data processing systems, communications systems, displays, industrial control applications, including road and rail signaling, and those embedded in military equipment, such as signal processors, electronic flight controls and digital engine control systems, are all potentially vulnerable to the EMP effect. Other electronic devices and electrical equipment may also be destroyed by the EMP effect. Telecommunications equipment can be highly vulnerable, due to the presence of lengthy copper cables between devices. Receivers of all varieties are particularly sensitive to EMP, as the highly-sensitive miniature high-frequency transistors and diodes in such equipment are easily destroyed by exposure to high-voltage electrical transients. Therefore radar and electronic warfare equipment, satellite, microwave, UHF, VHF, HF and low band communications equipment and television equipment are all potentially vulnerable to the EMP effect. Furthermore, high levels of directed electromagnetic energy may also be used to incapacitate or kill individuals, such as infantry forces.
Accordingly, there is a need to detect the presence of an EMP, a directed electromagnetic energy field, and specific forms of electromagnetic energy, such as radio frequency (RF) radiation. However, current RF detection devices of various designs either suffer from false positive alerts due to their sensitivity to local static discharge, or are relatively insensitive to transient electromagnetic pulse signals and RF signals of very short pulse duration. Current RF direction-finding (DF) devices also suffer from poor sensitivity and poor bearing resolution for transient electromagnetic pulse signals and RF signals of very short pulse duration. Current antennas used in RF-DF devices have either sensitivity limited to signals over a relatively narrow range of frequencies or sensitivity over a relatively limited range of signal polarization orientations.
Accordingly, it is, therefore, desirable to overcome the above problems and others by providing a device for detecting the magnitude, duration, repetition, and emission direction of electromagnetic radiation that may be harmful to a user or electrical device and informing the user of same. This information would be useful to provide sufficient time to protect against and neutralize continued electromagnetic radiation threats, both to electronic devices and individuals, in various environments and applications, including civilian, private, government, and military sector operations.